The present invention disclose an occupancy detection device and related system and method for detecting presence of at least one person at or near a table or in a swimming pool with at least one sensor indicating an occupancy status locally with at least one light source and communicating it to at least one mobile device by means of at least one wireless communication method. The occupancy detection device, with the use of at least one sensor, at least one additional status is communicated to at least one mobile device. A plurality of occupancy detectors can be connected in a mesh or a star network and communicate to at least one mobile device by a wireless communication method or combinations of a wired and a wireless communication methods.